Always remove the battery pack before you attempt to open a laptop. If the laptop is hot at all, wait to let it cool before dissassembling. In the case of overheating, check the fans and vents. Use your sense of smell to try and locate the source of heat. Follow manufacturers instructions for troubleshooting laptop overheating.
In case of a spill, switch of the machine and resist the temptation to turn it back on before you are sure that the spill has dried. Don't tilt the machine on its side or turn it upside down. Never use a hairdryer to dry out a spill; may melt your keys. It may be helpful to remove the keyboard and use an external keyboard to assess damage to the rest of the system.